Is May the New June for Fly Fishing in SW Montana?
- Lia Jones
- 3 minutes ago
- 2 min read
On the Big Hole River we have long counted on June as the prime month for summer fishing (most know this is when our famed salmonflies hatch). The river has usually reached its peak flows, and enjoys a long slow descend. People flock to the area; supporting local fly shops, occupying bar stools and filling up our local lodges, hotels, Air BnBs and campgrounds.
Traditionally, May is a cooler, less predictable month with higher, dirty water that make fishing challenging. Not to mention a good chance of rain/sleet/snow. Yet, recent years have shown a shift. May has been delivering some terrific fishing, raising the question: Is May becoming the new June for anglers? This change reflects broader shifts in weather patterns and water conditions that are reshaping the fishing calendar.
In recent years our regions has experienced:
Warmer early springs leading to earlier warming of water bodies
Reduced spring runoff due to less snowpack or altered precipitation patterns
More stable water levels in May compared to historical averages
These factors combine to create conditions that are more favorable for anglers in Southwest Montana. In 2025 the Mother's Day Caddis arrived early, and salmonflies began to hatch around May 29. Anglers who adapt to these changes can take advantage of a longer, more productive fishing season starting in May.
Decrease in Average High Water Levels since 2010
While we have seen some years with BIG water (remember 2011?), it seems that it goes away just as fast as it arrives. The graphs above show streamflows from 2010, 2015, 2020 and 2025. On average, the Big Hole experiences peak runoff during the first week of June. In 2025, we saw very early peak flows on May 14 (~ 3,200 cfs). By July 5, our flows were sitting just above 650 cfs. That makes for a pretty short season. Now, we do understand that every year is different, and we are doing our snow dances for more snow to come in the 2026 season. But, it feels like we are on track to have conditions that are similar to 2025.
So, to cut to the point, anglers should capitalize on May’s rising potential. If you are looking to book some guided fishing in 2026, don't count out May, or even April for that matter! You may be wondering, well if it is similar to last year, what kind of conditions can I expect this Spring? Well, there is chance of some pretty terrific dry fly fishing on Skwallas. For this opportunity, we generally check out the lower river (below Melrose). Timing for this could be as early as mid-April. After that, look forward to a couple of weeks of good streamer fishing. And, you probably won't have to throw a big, heavy, double articulated fly. As we move towards mid-May, there should be some more dry fly fishing with the arrival of the Mother's Day Caddis hatch.
Interested? Give us a call or shoot us a message to discuss availability, and get yourself on our calendar! Another bonus: guides are fresh and eager after a long winter.